Replacing radiator...DIY?

Robertb · 3 Oct 2019

My car has sprung a leak... a few drops of coolant on the floor under the OS radiator. I assume the radiator has failed, though I'm surprised as the car has mesh grilles fitted. There is a drip from where a hose joins the rad at the base of it, so maybe that but not had a chance to look properly and Im rarely that lucky.:sad:

Replacing the rad looks reasonably straightforward DIY - I changed a fan so I know my way round that bit of the car.

The bit I'm concerned about is draining all the coolant and refilling/burping, particularly given that I don't have a lift in the garage so would be working with axle stands. Is is as much of a faff as it looks?

Anyone got any tips/hints/tales of woe or encouragement to add?

Martin996RSR · 3 Oct 2019

I did this job earlier in the summer. I also have rad protection mesh but the rad was just a bit long in the tooth and had failed due to corrosion. It was easy enough to do.

I drained the coolant by removing a hose, I forget which one. I think there may even be drain plugs on the rads themselves, so hopefully someone can confirm.

Take the bumper off and the wheel arch liner and then take apart the assembly that includes the rad, aircon rad, and fan.

I used a cheap Ebay (but still new) rad and it's been fine. I think it was about £50. Bargain.

There are clips that go over the ends of the nodules that locate the rad and they are guaranteed to be badly corroded. New ones are hard to source. In the end I used slightly smaller than correct ones from D911.

In my case, to save weight, I removed my aircon rads and one of my fans. I don't have any overheating problems even on the hottest of days.

There are lots of different methods around for filling/burping the cooling system. I have a sloped driveway, so I park ar5e up, and fill, then run, then fill, then run. Once it jwon't take any more, I go for a drive that's long enough to open up the thermostat and then go back to the driveway and repeat.

The valve on the top of the coolant bottle is there to allow air in, so that coolant isn't prevented from being sucked into the system to where it's needed, so leave that valve open when you're trying to top up the system.

Don't stress about getting the bleeding exactly right. I follow the above procedure but still need to top off the coolant after each drive for a few days, then it stabilises.

Alex · 3 Oct 2019

Easy enough job, just time consuming. Don't worry about burping, just keep checking you level and do short drives then keep topping up until it settles.

I did a bit of a lame right up in my early days on here. Photos will help though:

http://911uk.com/viewtopic.php?t=96237

:thumbs:

wasz · 3 Oct 2019

It's dead easy.

I just whipped the old rad off and plugged the new one into the hoses.

Didn't bother draining from any specific point.

Just refill the coolant, I left the valve open and went for a drive stopping now and then to top up, and then close the valve.

Keep an eye on it the next few drives. Done this a few times for thermostat, the odd pipe and the rad, never had an air lock or any problem, probably better not to drain the whole system to be honest.

maldren · 3 Oct 2019

If you're draining the system (the antifreeze may be 20 years old!) you probably should replace the water pump and fit a low temp thermostat while you are at it.

Agree with above, getting rid of the remaining air takes a bit of time but is ok. Getting rid of all the old antifreeze is harder, I flushed mine out a couple of times.

Clanky · 3 Oct 2019

A word of warning when doing this.
Make sure its fully bled before a proper run. It seems to be an issue getting airlocks on flat engines which is why they advise vacuum filling the system after draining.
A friend of mine had a water pump change on a Subaru which suffered an airlock which in turn created a hot spot & boiled a head. Very costly!

Regarding the OP, it could be some of the ferrules on the coolant hoses starting to corrode. Some of them can be a proper PITA. Worth checking before ordering parts..

Robertb · 4 Oct 2019

Thanks Clanky- it was sounding encouraging until then, now I wonder if I'll get the indy to do it! Any clues to look/listen out for to make sure its bled properly and there are no airlocks?

The water pump was done 5 yrs/17k miles ago as part of the pre-delivery items, and I think much of the coolant was changed when they dropped the engine to do the AOS a couple of years later. Will look back at the invoices. LTT is a good shout.

Thanks everyone for the comments... seems its a game of two halves, with relatively straightforward fitment, but pitfalls involving the coolant, as I feared. If only there was a way of isolating the radiator inlet, like in a house!

I will take the arch liner out tomorrow and have a look... still clinging on to the possibility it may be a leaking connection

Alex · 4 Oct 2019

You'll be fine. Once you've driven round the block a few times and keep topping up it'll be sorted. Just keep your eye on it for a week.

Remember - the model before yours didn't even have a coolant system :grin:

Robertb · 5 Oct 2019

Well, it turns out it is dripping from the hose connection... the one at the base where it joins another hose from the rad.

So, no new rad needed which is good news but anyone know how to stop the leak... jubilee clip? :dont know:

Alex · 5 Oct 2019

Just take it off, clean up all mating faces then clamp back together (with a new jubilee clip if it's mullered.

maldren · 6 Oct 2019

and I always use stainless clips in areas vulnerable to corrosion.

infrasilver · 6 Oct 2019

often you can get a bit of corrosion between the rubber hose and the aluminium pipe/joint and makes it seep from between the two, just remove the joint and clean up any corrosion then replace, use a new jubilee clip if required.

If you are draing the front end, get the front as high as you can to minimise coolant loss, this will save time when bleeding the system.

Clanky · 6 Oct 2019

Robertb said:
Well, it turns out it is dripping from the hose connection... the one at the base where it joins another hose from the rad.

So, no new rad needed which is good news but anyone know how to stop the leak... jubilee clip? :dont know:

Do you mean the base of the radiator?
If so then there are no hose clips. The hose has a galvanised ferrule on the end with an 'O' ring on it to make the seal. These seem to be prone to corrosion & leakage.
You might get away with a new 'O' ring, but most likely will need new hoses & possibly the alloy pipework to go with it.
See: http://911uk.com/viewtopic.php?t=101052&highlight=pipework
Not that bad to do as I've done a few now. The main issue I found was with the galvy parts into alloy, causing corrosion & cold welding together but still leaking resulting in having to change them all together.

Robertb · 14 Oct 2019

Cheers guys, sounds exactly like that's happened.

Clanky- it's the hose at the front, forward of the radiator... the one you can see from under the front spoiler, through the air duct in the undertray.

JTT · 15 Oct 2019

HERE is a quick and easy way to drain all the coolant. Works a treat. You can pick up a vacuum filler on Amazon or Ebay cheap, doesn't have to be a fancy one, chinese ones work fine if your not using it daily. It makes the job very easy and safe.

Replacing radiator...DIY?

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